/Engine/Plugins/Animation/ControlRig/Source/ControlRig/Public/Sequencer/MovieSceneControlRigParameterSection.h
This function returns the active category index of the control, based upon what controls are active/masked or not If itself is masked it returns INDEX_NONE
int32 GetActiveCategoryIndex ( [FName](API\Runtime\Core\UObject\FName) ControlName ) const